Daniel Apai, University of Arizona A team of astronomers announced on April 16, 2025, that in the process of studying a planet around another star, they had found evidence for an unexpected atmospheric gas. On Earth, that gas – called dimethyl sulfide – is mostly produced by living organisms. In April 2024, the James Webb Space Telescope stared at the host star of the planet K2-18b for nearly six hours. During that time, the orbiting planet passed in front of the star. Starlight filtered through its atmosphere, carrying the fingerprints of atmospheric molecules to the telescope.

By comparing those fingerprints to 20 different molecules that they would potentially expect to observe in the atmosphere, the astronomers concluded that the most probable match was a gas that, on Earth, is a good indicator of life. I am an astronomer and astrobiologist who studies planets around other stars and their atmospheres. In my work, I try to understand which nearby planets may be suitable for life.

K2-18b, a mysterious world

To understand what this discovery means, let’s start with the bizarre world it was found in. The planet’s name is K2-18b, meaning it is the first planet in the 18th planetary system found by the extended NASA Kepler mission, K2. Astronomers assign the “b” label to the first planet in the system, not “a,” to avoid possible confusion with the star. K2-18b is a little over 120 light-years from Earth – on a galactic scale, this world is practically in our backyard. Although astronomers know very little about K2-18b, we do know that it is very unlike Earth. To start, it is about eight times more massive than Earth, and it has a volume that’s about 18 times larger. This means that it’s only about half as dense as Earth. In other words, it must have a lot of water, which isn’t very dense, or a very big atmosphere, which is even less dense. Astronomers think that this world could either be a smaller version of our solar system’s ice giant Neptune, called a mini-Neptune, or perhaps a rocky planet with no water but a massive hydrogen atmosphere, called a gas dwarf. Another option, as University of Cambridge astronomer Nikku Madhusudhan recently proposed, is that the planet is a “hycean world.” That term means hydrogen-over-ocean, since astronomers predict that hycean worlds are planets with global oceans many times deeper than Earth’s oceans, and without any continents. These oceans are covered by massive hydrogen atmospheres that are thousands of miles high. Astronomers do not know yet for certain that hycean worlds exist, but models for what those would look like match the limited data JWST and other telescopes have collected on K2-18b. This is where the story becomes exciting. Mini-Neptunes and gas dwarfs are unlikely to be hospitable for life, because they probably don’t have liquid water, and their interior surfaces have enormous pressures. But a hycean planet would have a large and likely temperate ocean. So could the oceans of hycean worlds be habitable – or even inhabited?

Detecting DMS

In 2023, Madhusudhan and his colleagues used the James Webb Space Telescope’s short-wavelength infrared camera to inspect starlight that filtered through K2-18b’s atmosphere for the first time. They found evidence for the presence of two simple carbon-bearing molecules – carbon monoxide and methane – and showed that the planet’s upper atmosphere lacked water vapor. This atmospheric composition supported, but did not prove, the idea that K2-18b could be a hycean world. In a hycean world, water would be trapped in the deeper and warmer atmosphere, closer to the oceans than the upper atmosphere probed by JWST observations. Intriguingly, the data also showed an additional, very weak signal. The team found that this weak signal matched a gas called dimethyl sulfide, or DMS. On Earth, DMS is produced in large quantities by marine algae. It has very few, if any, nonbiological sources. This signal made the initial detection exciting: on a planet that may have a massive ocean, there is likely a gas that is, on Earth, emitted by biological organisms.

Scientists had a mixed response to this initial announcement. While the findings were exciting, some astronomers pointed out that the DMS signal seen was weak and that the hycean nature of K2-18b is very uncertain. To address these concerns, Mashusudhan’s team turned JWST back to K2-18b a year later. This time, they used another camera on JWST that looks for another range of wavelengths of light. The new results – announced on April 16, 2025 – supported their initial findings. These new data show a stronger – but still relatively weak – signal that the team attributes to DMS or a very similar molecule. The fact that the DMS signal showed up on another camera during another set of observations made the interpretation of DMS in the atmosphere stronger. Madhusudhan’s team also presented a very detailed analysis of the uncertainties in the data and interpretation. In real-life measurements, there are always some uncertainties. They found that these uncertainties are unlikely to account for the signal in the data, further supporting the DMS interpretation. As an astronomer, I find that analysis exciting.

Is life out there?

Does this mean that scientists have found life on another world? Perhaps – but we still cannot be sure. First, does K2-18b really have an ocean deep beneath its thick atmosphere? Astronomers should test this. Second, is the signal seen in two cameras two years apart really from dimethyl sulfide? Scientists will need more sensitive measurements and more observations of the planet’s atmosphere to be sure. Third, if it is indeed DMS, does this mean that there is life? This may be the most difficult question to answer. Life itself is not detectable with existing technology. Astronomers will need to evaluate and exclude all other potential options to build their confidence in this possibility. The new measurements may lead researchers toward a historic discovery. However, important uncertainties remain. Astrobiologists will need a much deeper understanding of K2-18b and similar worlds before they can be confident in the presence of DMS and its interpretation as a signature of life. Scientists around the world are already scrutinizing the published study and will work on new tests of the findings, since independent verification is at the heart of science. Moving forward, K2-18b is going to be an important target for JWST, the world’s most sensitive telescope. JWST may soon observe other potential hycean worlds to see if the signal appears in the atmospheres of those planets, too. With more data, these tentative conclusions may not stand the test of time. But for now, just the prospect that astronomers may have detected gasses emitted by an alien ecosystem that bubbled up in a dark, blue-hued alien ocean is an incredibly fascinating possibility. Regardless of the true nature of K2-18b, the new results show how using the JWST to survey other worlds for clues of alien life will guarantee that the next years will be thrilling for astrobiologists. Daniel Apai, Associate Dean for Research and Professor of Astronomy and Planetary Sciences, University of Arizona This article is republished from The Conversation under a Creative Commons license. Read the original article.

Wendy Whitman Cobb, Air University Jared Isaacman, billionaire, CEO and nominee to become the next NASA administrator, faced questions on April 9, 2025, from members of the Senate Committee on Commerce, Science, and Transportation during his confirmation hearing for the position. Should the Senate confirm him, Isaacman will be the first billionaire – but not the first astronaut – to head NASA. Perhaps even more significant, he will be the first NASA administrator with significant ties to the commercial space industry. As a space policy expert, I know that NASA leadership matters. The head of the agency can significantly shape the missions it pursues, the science it undertakes and, ultimately, the outcome of America’s space exploration.

An unconventional background

At 16 years old, Isaacman dropped out of high school to start a payment processing company in his basement. The endeavor succeeded and eventually became known as Shift4. Though he found early success in business, Isaacman also had a love for aviation. In 2009, he set a record for flying around the Earth in a light jet, beating the previous record by more than 20 hours. While remaining CEO of Shift4, Isaacman founded another company, Draken International. The company eventually assembled the world’s largest fleet of privately owned fighter jets. It now helps to train U.S. Air Force pilots. In 2019, Isaacman sold his stake in Draken International. In 2020, he took Shift4 public, making him a billionaire. Isaacman continued to branch out into aerospace, working with SpaceX beginning in 2021. He purchased a crewed flight on the Falcon 9 rocket, a mission that eventually was called Inspiration4. The mission, which he led, represented the first private astronaut flight for SpaceX. It sent four civilians with no previous formal space experience into orbit. Following the success of Inspiration4, Isaacman worked with SpaceX to develop the Polaris Program, a series of three missions to help build SpaceX’s human spaceflight capabilities. In fall 2024, the first of these missions, Polaris Dawn, launched. Polaris Dawn added more accomplishments to Isaacman’s resume. Isaacman, along with his crewmate Sarah Gillis, completed the first private spacewalk. Polaris Dawn’s SpaceX Dragon capsule traveled more than 850 miles (1,367 kilometers) from Earth, the farthest distance humans had been since the Apollo missions.

The next adventure: NASA

In December 2024, the incoming Trump administration announced its intention to nominate Isaacman for the post of NASA administrator. As NASA administrator, Isaacman would oversee all NASA activities at a critical moment in its history. The Artemis program, which has been in progress since 2017, has several missions planned for the next few years. This includes 2026’s Artemis II mission, which will send four astronauts to orbit the Moon. Then, in 2027, Artemis III will aim to land on it.

But, if Isaacman is confirmed, his tenure would come at a time when there are significant questions about the Artemis program, as well as the extent to which NASA should use commercial space companies like SpaceX. The agency is also potentially facing funding cuts. Some in the space industry have proposed scrapping the Artemis program altogether in favor of preparing to go to Mars. Among this group is the founder of SpaceX, Elon Musk. Others have suggested canceling NASA’s Space Launch System, the massive rocket that is being used for Artemis. Instead, they argue that NASA could use commercial systems, like SpaceX’s Starship or Blue Origin’s New Glenn. Isaacman has also dealt with accusations that he is too close to the commercial space industry, and SpaceX in particular, to lead NASA. This has become a larger concern given Musk’s involvement in the Trump administration and its cost-cutting efforts. Some critics are worried that Musk would have an even greater say in NASA if Isaacman is confirmed. Since his nomination, Isaacman has stopped working with SpaceX on the Polaris Program. He has also made several supportive comments toward other commercial companies. But the success of any of NASA’s plans depends on having the money and resources necessary to carry them out. While NASA has been spared major cuts up to this point, it, like many other government agencies, is planning for budget cuts and mass firings. These potential cuts are similar to what other agencies such as the Department of Health and Human Services have recently made. During his confirmation hearing, Isaacman committed to keeping the Artemis program, as well as the Space Launch System, in the short term. He also insisted that NASA could both return to the Moon and prepare for Mars at the same time. Although Isaacman stated that he believed NASA had the resources to do both at the same time, the agency is still in a time of budget uncertainty, so that may not be possible. About his relationship with Musk, Isaacman stated that he had not talked to Musk since his nomination in November, and his relationship with SpaceX would not influence his decisions. Additionally, he committed to carrying out space science missions, specifically to “launch more telescopes, more probes, more rovers.” But since NASA is preparing for significant cuts to its science budget, there is some speculation that the agency may need to end some science programs, like the Hubble space telescope, altogether.

Isaacman’s future

Isaacman has received support from the larger space community. Nearly 30 astronauts signed a letter in support of his nomination. Former NASA administrators, as well as major industry groups, have signaled their desire for Isaacman’s confirmation. He also received the support of Senator Ted Cruz, the committee chair. Barring any major development, Isaacman will likely be confirmed as NASA administrator by the Senate in the coming weeks. The Committee on Commerce, Science, and Transportation could approve his nomination once it returns from a two-week break at the end of April. A full vote from the Senate would follow. If the Senate does confirm him, Isaacman will have several major issues to confront at NASA, all in a very uncertain political environment. Wendy Whitman Cobb, Professor of Strategy and Security Studies, Air University This article is republished from The Conversation under a Creative Commons license. Read the original article.

Dr. Ronald Premuroso, Western Governors University School of Business With stock market charts resembling the contours of a roller-coaster ride in recent days, many Americans could be forgiven for eyeing their 401(k)s with a little concern. Retirement savings are crucial to the financial well-being of millions of especially older people in the U.S., so the concern is understandable. But just how worried should people be by market fluctuations? And just how big a hit do 401(k)s take when markets fall? The Conversation turned to Western Governors University’s Ronald Premuroso, an expert in this area, for answers.

What is a 401(k)?

Simply put, a 401(k) is an employer-sponsored retirement savings plan in which employees contribute a portion of their compensation on a tax-deferred basis. The employee is eligible at any age to contribute to a 401(k) plan and has the option to pay into these plans throughout their employment. Many employers match some or all of an employee’s contributions, making the plan even more attractive.

What about withdrawals?

Under Internal Revenue Service rules, someone with a 401(k) is required to start making monetary withdrawals from their plan when they reach age 73. Some people start withdrawing at an earlier age. Someone with a 401(k) can withdraw funds from the plan early, and at any time. But the money amounts withdrawn will typically be deemed taxable income. In addition, those age 59 and a half and under will likely face a 10% penalty on the withdrawal, unless the employer’s plan allows for hardship distributions, early withdrawals or loans from your plan account. The IRS has specific rules for these early withdrawals; if you find yourself in this situation, you should get help from a tax professional. All withdrawals starting at age 73, which tax professionals call “RMDs,” are then taxable in retirement – presumably at a lower tax rate than the employee was subject to while employed and working. So these withdrawals starting at age 73 can be a very tax-efficient way of financial planning, including personal income tax planning, for later in life, especially in one’s retirement years. Again, it’s important to get help from a tax professional to make sure you meet the IRS’ RMD dollar withdrawal requirements once you start withdrawing. In calendar-year 2025, the most that an employee can contribute to a tax-deferred 401(k) plan annually is US$23,500, including the employer’s match. “Super catch-up contributions are allowed for employees over the age of 50 to their employer’s 401(k) plan each year indexed to inflation. In 2025, super catch-up contributions allow individuals age 50 and older to contribute an additional $7,500 beyond the standard limit, bringing their total annual contribution to $31,000. For those turning age 60, 61, 62 or 63 in 2025, the SECURE Act 2.0 allows a higher catch-up contribution limit of $11,250, resulting in a total allowable contribution of $34,750 in 2025.

When and why did 401(k)s become popular?

Before 1978, retirement savings options were limited. In 1935, Congress created the Social Security Retirement Plan. This was followed by the Employee Retirement Income Security Act of 1974, which created individual retirement accounts, or IRAs, as a way for employees to save tax-deferred money for their retirement. 401(k) plans became popular with the passage of the Revenue Act of 1978 by Congress. Congress saw 401(k) plans at that time as an alternative way to supplement Social Security benefits that all eligible Americans are entitled to receive upon retirement. In 1981, the IRS issued new rules and regulations allowing employees to fund their 401(k)s through payroll deductions. This significantly increased the number of employees contributing to their employers’ 401(k) plans. As of September 2024, Americans held $8.9 trillion in 401(k) plans, according to the Investment Company Institute. A study published by the Pension Rights Center toward the end of 2023 using data provided by the Bureau of Labor Statistics concluded that 56% of all workers – including private sector and state and local government workers – participate in a workplace retirement plan. That equates to 145 million full- and part-time workers.

How are 401(k) plans affected by market rises and falls?

Contributions to a 401(k) are typically invested in a variety of financial instruments, including in the stock market. Most 401(k) plans offer investment options with varying levels of risk, allowing employees to choose based on their personal comfort levels and financial goals. Employers typically outsource the management of these 401(k) plans to third parties. Some of the largest companies managing 401(k) funds on behalf of employers and employees include Fidelity Investments, T. Rowe Price and Charles Schwab, to name just a few. Because many of these investments are tied to the stock market, 401(k) balances can rise or fall with market fluctuations.

Should I be worried about the stock market tanking my 401(k)?

It depends on when you started making contributions, when you plan to retire and when you expect to start making withdrawals. Employees with 401(k) accounts should only be worried about falling stocks if they need the money right now – either for retirement living expenses or for other emergency reasons. If you don’t need to take money out soon, there’s usually no reason to panic. History has shown that markets can rebound quickly; short-term drops often don’t signal long-term trends. Over time, the stock market has experienced many periods of falling stock prices: the bursting of the internet bubble of 2000; the period after the events of 9/11; and the U.S. and global banking crisis of 2007-2010, to name but three. But overall, over time, stock market returns have averaged 9% from 1994 to 2024, and this includes the periods of falling stock prices mentioned above. So even if you are a baby boomer heading for retirement and your 401(k) has taken a hit in recent weeks, don’t panic. Bear in mind the truism that stock markets can always go down as well as up. History suggests that in the long run, depending upon your plans and timing for retirement, working together with a trusted financial adviser strategically with regard to your 401(k) retirement savings is a good approach, especially during periods like we have seen in recent weeks in the stock market. This article is for informational purposes and does not constitute financial advice. Consult with a qualified financial adviser before making financial decisions. Dr. Ronald Premuroso, Accounting Instructor, Western Governors University School of Business This article is republished from The Conversation under a Creative Commons license. Read the original article.